Analytical study of low-concentration gases

Abstract A method has been developed for determination of atmospheric nitric acid by micro high-performance liquid chromatography (MHPLC). Gaseous nitric acid was collected via a Millipore filter in distilled water or 0.2% sodium hydroxide solution, concentrated in a precolumn and determined by MHPLC. The method is rapid and simple with a collection efficiency of more than 90% and a coefficient of variation of less than 5%. The recovery of the precolumn concentration step was as high as 98.8% and the coefficient of variation was only 2%. The correlation coefficient between the results obtained by MHPLC and by the conventional sodium salicylate method was 0.92. The detectable range by the MHPLC method was 0.5–5.0 ng/1 as nitrate nitrogen when 200 1 of air were sampled. The method enabled determination of 0.18–3.3 ppb (at O°C, 760 mmHg) of gaseous nitric acid in urban air and was found to have sufficient accuracy for environmental atmospheric determinations.